title: Obesity and risk of bladder cancer: a meta-analysis of cohort studies.
abstract: OBJECTIVE
  Previous epidemiologic studies demonstrated that obesity might associated with the risk of bladder cancer. However, many of the actual association findings remained conflicting. To better clarify and provide a comprehensive summary of the correlation between obesity and bladder cancer risk, we conducted a meta-analysis to summarize results of studies on the issue. Stratified analyses were also performed on potential variables and characteristics.
  
  
  METHODS
  Studies were identified by searching in PubMed and Wanfang databases, covering all the papers published from their inception to March 10, 2013. Summary relative risks (SRRs) with their corresponding 95% confidence intervals (CIs) were calculated by either random-effect or fixed-effect models.
  
  
  RESULTS
  A total of 11 cohort studies were included in our meta-analysis, which showed that obesity was associated with an increased risk for bladder cancer in all subjects (RR=1.10, 95% CI=1.06-1.16; p=0.215 for heterogeneity; I2=24.0%). Among the 9 studies that controlled for cigarette smoking, the pooled RR was 1.09 (95% CI 1.01-1.17; p=0.131 for heterogeneity; I2=35.9%). No significant publication bias was detected (p = 0.244 for Egger's regression asymmetry test).
  
  
  CONCLUSIONS
  Our results support the conclusion that obesity is associated with the increased risk of bladder cancer. Further research is needed to generate a better understanding of the correlation and to provide more convincing evidence for clinical intervention in the prevention of bladder cancer.
authors.affiliation: Department of General Surgery, Childrens Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Qin
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Xiang-Yi
authors.initials: XY
authors.lastname: Zheng
mesh_terms: D015331:Cohort Studies; D006801:Humans; D009765:Obesity / Q000150:complications*; D011379:Prognosis; D012307:Risk Factors; D001749:Urinary Bladder Neoplasms / Q000209:etiology*